Current-reinforcing means.



R. C. BROWNE. CURRENT REINFORCING MEANS. APPLIOA'HN FILED MAY 25, 1907.

Ptented June 7 es es.'

'RALPH C. BROWNE, OF SALEM, MASSACHUSETTS, ASSIGNOR T0 JOHN ABBOTT, OFWINCHESTER, MASSACHUSETTS.

C"UBRENT-EtIEINIEORIGIN-Gr` MEANS.

augmenting the energy in the varying cur-r rent circuit, by addingthereto and in synchronism therewith, additional energy derived from abattery or other electricalgenerator. In telephony practical resultshavebeen secured in instruments of this character by causing the current, tobe reinforced in 4the telephone circuit, to act upon a diaphragm throughthe agency of the variable receiving magnet, which diaphragm isconnected to an electrode'between which and a second fiiged electrode isplaced the variable resistance medium.' Said electrodes and saidresistance mediumv are arranged in series in a' local lbattery circuit,so that when the diaphraglufis vibrated,'it causes fluctuations in thelocal -or battery circuit in synchronism with the fluctuations of thecurrent in the telephone circuit.. In instruments such as described, thediaphragm is madeof magnetic material which is fairly rigid and heavy,and its inertia must be overcome by the magnetic field -induced by thetelephone current acting on the variable receiving magnet before thevdiaphragm is vibrated. The electrode which isaifixed to the diaphragmto movel therewith, adds to the A weight which must be moved by themagnet,

and if, as in most cases, it is made of pol-A ished carbon .or likematerial, it is apt to become roughened and less effective. Tele phonecurrents are feeble at best, and they grow weaker with the length of thetelephone line in consequence of the increasedv resistance thereof andof leakages and other losses. On account of the feebleness of thecurrent in a telephone circuit, the'diaphragm and the electrodeconnected thereto, have a very slight. movement, and the two electrodestherefore must be brought very close Specification of Letters Patent.

together sothat the pressure 'on the resistance medium may effect even asmall part of the dead resistance between them. The closer theelectrodes are brought together, the lower the resistance of theintervening medium, and the possible range of the instrument iscorrespondingly limited. The close adjacency of the electrodes kgreatlylimits the amount of battery power that may be 'employed `'without suchharmful results as burning or heating etc., and moreover, the closer theelectrodes are brought together, the greater isth'e danger of the resistance medium packing,

The objectof this invention is to improve such current reinforcing orrenewing means by increasing their sensitiveness and their range ofaction, and by enhancing their efficiency, and durability. This isaccomplished by employing in conjunction -with a variable magnetarranged in the telephone circ'uit or sequence of circuits, an armatureor movable pole piece operating upon a thin resistance medium 'throughwhich the current flows between electrodes so placed that the path ofthe current is substantially at right angles to the lines'of pressure ofthe armature o1" movable'pole piece upon the resikstanee medium. The twoelectrodes are stationary and neither of them. is carried by the movablepole iece or armature, -nor vibrated by the laction thereof. Theresistance medium, which is preferably carbon in a comminuted form, isarranged in a thin layer between insulated retaining walls, of which oneor both may be made of light Hexible material, such as mica or othersuitable substance. Thus .I dispense with the employment of a magneticdiaphragm and the necessity of overcoming its inertia. By arranging theresistance medium `in a thinlayer, as described, and employingstationary electrodes, I secure the greatest possible scnsitiveness inthe resistance medium, and.

Patented June 7, 1910.

Application filed May 25, 1907, Serial No. 375,573.

On the accompanying drawings,-'Figurc l 2 scones 1 representsdiagrammaticallythe electric connections of the reinforcing instrument,

associated with a telephone circuit at animtermediate point thereof.Fig. 2r epres`ents a magnified section through the receptacle containingthe variable resistancemedium..

Fig. 3 represents a magnified vertical section of another form oflnstrument embodying the invention.

The 'electrodes and the variable 'resistance medium to be hereinafterdescribed aredesigned to be` connected in a main circuit 10,

as illustrated conventionally in Fig. 1, said main circuit includinga'battery or source of power. as at 11. The magnetizatio'nvarying coil b.is arranged to be connected with another main circuit section 12. 'Inthe circuit 10 may be included the primary windings 13 13 of inductioncoils, the secondary windings. 14 14 of which are included in the maintelephonecircuit 15. As..

illustrated, the apparatus is'shownv as being placed in the middle ofthe circuit 15 the which includes the coil b is in position to beoperated from either end of the telephone circuitor s aid sections 17 17there being inv the section 15 at eaclil end, areceiver 20.

The telephone currents passing through the-'coil b cause a variation inthe field of the variable magnet so that the pole pieces a a2 areattracted 1n accordance with Such variation, to effect a similarvariatlon in thecompression of the resistance medium. Consequentlytelephonie currentsv synchronous with those in the main circuit 15, areset up in the circuit 1.0, and by reason. of the coils 13, 13 iniductiverelation to the coils 14, 14, the telephonie currents inthe maintelephonic circuit are renewed or reinforced in a manner now wellunderstood.

In Figs. 2 and 3 I have illustrated an embodimentof the invention inwhich I employ a magnet e of the horse-shoe type. This has the parallelarms e e which are apertured to receive the inwardly extending polepieces f which are formedy of tubular magnetic material, such as softiron. Upon these pole pieces-are supported the spools g of twomagnetization-varying coils g g Whose axes are in alinement. These twocoils may be placed inseries in the main telephonie circuit or in ,oneof the sectins thereof, as

`for instance in the brid e 12. 4Between the adjacent ends of the co sis. placed a receptacle h of substantially the construction shownlsinFig. 2. Said receptacle contains a thin layer@ of a suitable resistancemedium suchv asgranular carbon, with separate staf tionary electrodes dd arranged in a line transverse to the axes of the coils. layerispreferably about one-tenth of an inch in thickness, and the retainingwalls c c are preferably thin' (say .-001 of an inch in thickness) andhave smooth4 surfaces. indthat .micais an excellent -material`for 75these walls:A Said walls are spaced apart by' an intervening frame c2 ofinsulating ma- 'terial` to which they. are clamped lby outer frames c303, and the frames or walls 'consti-ff tute -a chamber or receptacle forthe resist- 8e.. ance of the medium. 'The electrodes may consist vofstampings of this metal foi'l (preferably platinum) which are pointedattheir ends, and they are supported by the framec2 so as to centralize orfocus the flow of current through the variable resistance medium inlines transverse tothe axes or median 'lines of the pole pieces i z'.The receptacle is mounted upon a support attached to a l neutral pointofthe ma net e, said support 9'0 comprising the two memers j jvclamped.to-4 gether by a screw j to receive and rigidly support Saidreceptacle. lAttached to the outer .faces of the two flexible retainingwalls of the receptacle, are two movable polepieces i z' arranged withtheir axesin alinement with the axes of the pole pieces f f, but out ofcontact therewith as shown. The movable pole pieces z' z' are formed oflight tubing having solid'bos'ses or inner endsv 100 and have but littleinertia. The movable pole pieces are attached in any suitable mannertothe retaining walls, but I find that with advantage they may becemented to a facing of fine or delicate silk fabric which is in turncemented to said walls. By reason yof magnetic induction, the polepieces become magnetized more or less, according to; the strength of themagnet e, and" thereby attract each other with a certain force to causethe variable resistance medium to be compressed more or less. When thetelephonie current passes through the coils' g g,-the magnetic ieldiseither increased or decreased thereby causing a variation in the forcewith which said pole pieces z' i attract each other. The pressure u onthe resist'- ance medium is effected direct y against both faces thereofby the variation in the telephonic current, and as said medium vis-inavery thin layer with the electrodes widely separated, thegreatestpossible microphonic action -is had, and a` maximum electromagneticforce is utilized for reinforcing the telephonie currents in the maintelephonie circuit. The electrodes which are in contact with thevariable resistance medium are separated a distance several timesgreater than the thickness ofthe layer of the variable resistancemedium, and the resistance of The 7o the medium may be as great orgreater than the line resistance of the battery circuit.

I have not attempted to show the parts in their relative dimensions, asthese will Vary according to circumstances, nor have I 'attempted todescribe themodications of the apparatus inl which the invention may beembodied. It Will be understood by those to Whom this speciticati'on isaddressed,that the illustrated details of construction and arrangementmay be greatly varied Without departing from the spirit and scope of theinvention, that the l reinforcing means herein described and claimed maybe employed for reinforcing all kinds of Varying currents in electricalsystems for the transmission of intelligence, and that the phraseologywhich I employ is for the purpose of description arid not of limitation.

Having thas explained the nature of my said invention and described awayofjconstructing and using the same, although Without attempting to setforth all-0f the forms in which it ma be made, or all of the modes `ofits use, Iydeclare that What I claim is -v y l. A current retransmittingand reinforcing apparatus comprising a variable magnet having opposingfixed pole pieces; a receiving or magnetization-varying coil around eachpole `of said magnet for 'varying` its field; a variable resistancemedium; opposing movable pole pieces or armatures in the eids ofA saidfixed pole pieces to impart pressure to both sides or facesof saidresistance medium; and electrodes for said resistance medium arranged ina line transverse to the lines of pressure of said movable pole pieceson said resistance medium.

2. A current retransmittingand reinforcing appara-tus, comprising avariable magnet having opposing fixed pole pieces; a receiving ormagnetization varying coil around each pole of said magnet for varying.its field; a variable resistance medium; opposing movable pole piecesor' armatures in the fields of said fixed pole pieces' to impartpressure to both sidesor faces of said resistance medium; a. receptaclefor said resistance medium, and a iiXed support' for said receptacle..

3. A current retransmittingand reinforcing apparatus, comprising avariable magnet having opposing fixed pole pieces; a receiving ormagnetization -varying coil around each poie of said magnet for varyingits ield; a variable resistance medium; opposing movable pole pieces .orarmatures in the fields of said fixed 'pole ieces to impart pressure toboth sides `or aces of said resistance medium; said pole pieces allbeing arranged in axial' alinement; electrodes mountedv in alinetransversetothe axes of said pole pieces; and a receptacle forreceiving and supporting said resistance medium and said electrodes.

In testimony vwhereof I have affixed my i signature, inpresence of twowitnesses.

RALPH C..BROWNE.

wWitnesses MARCUS lB. MAY, E. BATCHELDER

